Prevalence of thyroid autoimmunity in first-degree relatives of patients with celiac disease

Aim Patients with celiac disease (CeD) are prone to develop other autoimmune diseases such as autoimmune thyroid disease and type 1 diabetes. While 7.5% of first-degree relatives (FDRs) of patients with CeD develop CeD, it is not clear whether FDRs of patients with CeD are at higher risk of developing autoimmune thyroid disease. Methods In this prospective case-control study, we recruited 194 FDRs (males 53.1%) of 91 patients with CeD and 140 age-matched healthy controls (males 76.4%). They were screened for CeD using anti-tissue transglutaminase antibodies (anti-tTG Ab) and thyroid disease using a symptom questionnaire, anti-thyroid peroxidase antibodies (anti-TPO) and serum thyroid-stimulating hormone (TSH). Subjects having positive anti-TPO but a normal TSH were classified as having thyroid autoimmunity and those with elevated TSH with or without positive anti-TPO Ab were classified as having autoimmune thyroid dysfunction. Results The prevalence of thyroid autoimmunity and autoimmune thyroid dysfunction in FDRs was significantly higher than that in healthy controls (17.5% vs. 5.0%, p < 0.01; 11.8% vs. 3.5%, p < 0.01), respectively. A significantly higher number of FDRs had a positive anti-tTG Ab in comparison with controls (13.9% vs. 2.2%, p < 0.001). Amongst FDRs having thyroid autoimmunity, 44.1%, 47.0% and 8.8% were siblings, parents and children of patients with CeD, respectively. Familial clustering was seen only in 1 family. Conclusion FDRs of patients with CeD have 3-fold higher risk of developing autoimmune thyroid disorders and associated thyroid dysfunction. Therefore, it is advisable for early screening of FDRs for CeD and associated thyroid autoimmune through screening measures.